Arc-regulating system.



I H. nouns. ARC REGULATI NG SYSTEM. APPLICAUOfl FILED SEPTFIO. I917.

Patented Apr. 1,191&

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ATTORNEY UNITED STATES PATEN HARRY HOLLIS, OF LEBANON, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

ARC-BEGULATING SYSTEM.

Specification of Letters Patent.

Patented Apr. 1, 1919.

Application filed September 10, 1917. Serial No. 190,506.

useful Improvement in Arc-Regulating Systems, of which the following is a specification.

My invention relates to electric furnaces of the arc type and particularly to means for regulating the arcs thereof.

One object of my invention is to provide a regulating means for a furnace of the above indicated character that shall employ the relative bucking effects of difierentially acting generator field-magnet windings to control the are through the power source of an electrode-actuating motor.

Another object of my invention is to provide means for controlling the arc in an electric furnace that shall be accurate in its degree of response to current fluctuations and that shall not require interruption of the circuit of the actuating motor.

A further object of my invention is to provide a single means for controlling the movement of an electrode to and from its arcstriking position and for maintaining a predetermined arc.

In practising my invention, I employ a separately-excited direct-current motor for operating-the electrode. The armature of this motor is connected in closed-circuit relation to the terminals of a differentiallywound separately-excited generator. The magnitude and direction of the exciting flux of the generator may be controlled by adjustingthe field-winding rheostats that are connected in circuit with the opposing fieldmagnet coils of the generator. Thus, the amount of movement and the direction of rotation of the motor, and, consequently. the regulation of the electrode may be controlled.

This control is made responsive to fluctuations in the are through a series transformer that is connected in the furnace supply circuit and a current-responsive relay the Winding of which is connected in series with the secondary of the transformer. The currentresponsive relay controls a difi'erential relay that operates in accordance with are varia tions, to intermittently short circuit one of the generator field rheostats' and to thereby permit dominance of the one or the other of v the field magnets of the generator.

Short or inconsequential fluctuations of the arc current will not change the position of the electrode because prevented by the inertia of the motor armature and the intermittent surges of oppositely directed flux in the field of the generator. Only a considerable change of arc current will effect the operation of the electrode-actuating motor.

The single figure of the accompanying drawing is a diagrammatic view of an electric furnace provided with a control system embodying my invention.

A furnace 1, containing a charge of material 2, is provided with a movable electrode 3 and is adapted to be supplied with current from the secondary circuit 4, of a transformer 5. the primary winding of which is connected to a main supply circuit 6.

The electrode 3 is operatively connected, by a drum-and-cable mechanism 7 or other suitable means, to a direct-current motor 8.

The field-magnet Winding 9 of the motor 8 is supplied, through conductors 10 and 11, with current from a compound-Wound generator 12 that also supplies current, through conductors 11 and 13, to coils 14 and 15 of a differential relay 16 and through rheostats 25 and 26 and conductors 34 to the fieldmagnet windings 23 and 24 of a generator 18.

The rotatable members of compoundwound generator 12, an alternating-current driving motor 17 and the differentiallywound generator 18, are mounted on a shaft 19 and are adapted to operate at a constant speed.

The armature 20 of the motor 8 and the armature 21 of the generator 18 are connected in series relation in a closed circuit by means of conductors 22. The fluxes produced by the currents traversing the oppositely-connected field-magnet windings 23 and 24 of the generator 18 may be regulated by their respective rheostats 25 and 26 to control the polarity of the said generator.

' generators 12 and -,relatively greater current to flow in the the contact memb supplying secondary circuit l of the transformer 5. Current for the lay 29mm! be adjusted to any desired value by a suitable rheostat or by varying the number of turns of the winding 32 thereof. The contact members 33' of the relay 29 are adapted to alternately connect and disconnect the coil 14: of the differential relay 16 from the circuit 13.

l/Vith current flowing the rheostats 25 and 26 properly adjusted, the operation of my device is as follows.

The motor 17 is energized; to drive the supplies current to the field-magnet winding '9 of the motor 8, to-the field-magnet wind ings 23 and 24 of generator 18, and to the differential relay coils '14 and 15.

direction, to the armature 20' of the motor 8 to cause into engagement'with the material 2. Upon engagement of terial .2, current of greater value than the .n'ormal operating currentof the arc will causing s'uiliappended claims.

flow in the, circuit 1, thereby cient current to flow in the circuit 30 to actuate the relay 29 to p ers 33. Current will then of the difit'erential'reflow in thewinding 1 1 d be actuated to efi'ect lay;16 which will thus engagement of This short-circuits the rheostat 26 to cause a.

field-magnet winding 24: than in the winding 23 and reverses the polarity of the generator 18. The reversed curre'nt-inthe circuit 22 operates to reverse the direction of rotation ofthe armature 20 and thereby raises the electrode 3. raised to a point just beyond the point at which the arc current reaches its normal value, the contact members 33 are disengaged by reason of the reduced current in the circuit 30, thereby reversing the polarity of the generator18 and tending to lower the electrode 3. Y

When the electrode, in response to the above action, is lowered to a point ust below the point at which the arc current has its, normal value,

the contact members. 33 become engaged by reason of the increased cur: rent in the circuit 30, and the polarity of the generator 18 is again reversed. This action of changing polarity of the generator 18 will continue very rapidly when normal arc current flows, very small changes in position of the electrode causing a bucking action in the generator windings, and,.by reason of the inertia of the armature 20 of the 7 motor 8', keeping the are of substantially 2O prevents its response to inconsequential.

The inertia of the armature constantvalue.

' fluctuations, but a considerable change in the arc current will permit the generator in the circuit 6 and 18, the former of which The generator 18 supplies current", in the proper the latter to lower the electrode 3 the electrode3 and the ma efl'ect. engagement of the contact members 28.'

When the electrode .is

The furnace operation may be discon-l tinued by adjusting one or both of the rheo stats 25 and 26 to such values that the opposing fluxes of the windings 23 and 2 1 are 1 neutralized, and the electrode mayberaised or lowered by ad usting the 'rheostats until the flux of one ofthe windings=23 and 24is greater than the other. The above described invention may be similar manner, to each electrode of a threephase system. y v

While I have shown and'described a particular arrangement of my invention, it is tobe understood that many changes may be effected therein without departing from the spirit and scope thereof, as set forth in the I claim as my invention:

1. In an electric arc furnace, an electrode, means normally active. for actuating the electrode, and independent means responsive to variations in the length of the are for controlling the normally active means.

2. In an electric arc furnace, an electrode, means for actuating the electrode, power means normally connected to said actuating .means, and means responsive to the current arrangement of my I readily adapted, in a 4. In an electric'furnace, the comblnation with a movable electrode and a motor for actuating the electrode, of a difierentially-' wound generator for'supplying power to the actuating motor, and means controlling the a I effectiveness of the windings ofrthe gen-v erator;

5. In an electric furnace, the combination with a movable electrode and a motor for actuating the electrode, of a difl'erentiallywound generator for supplying power to the actuating motor, and means responsive to the current traversing the electrode for controlling the effectiveness of the windings of the generator. Y

v6. In an electric furnace, the combination with avmovable electrode and a motor for actuating the electrode, of a differentiallyisothe actuating motor, a differential relay for varying the ampere turns of one of the windings of the generator, and means responsive to the current traversing the electrode for controlling the differential relay.

8. In a regulating device, the combination with an actuating devlce, of means for actuating said device, a differentially-wound generator for supplying power to the actuating device, and means responsive to the movement of the actuating device for controlling the difi'erential windings of the generator.

,9. In an electric furnace, the combination with an electrode and means for actuating the electrode, of independent means responsive to the current traversingthe electrode for governing said actuating means to effect movement of the electrode to its arcstriking position and normally active to maintain a predetermined arc.

10. The combination with a movable electrode and a motor for actuating the electrode, of a generator having two windings so connected that, when no current traverses the electrode, the motor is actuated by the generator to move the electrode to its arc-striking positiomand means for so neutralizing one of the windings that the electrode is maintained in a predetermined po-' sition when current traverses the same.

11. In an electric apparatus, the combination with an adjustable member and elec-,

trical means for actuating said member, of independent governing means for said actuating means normally electrically connected thereto, and means for rendering said governing means active under predetermined conditions.

12. In an electric apparatus, a conducting member, electrical means for moving the conducting member, and independent governing means normally connected to the electrical means for governing the operation of the electrical means'in accordance with the current flowing through the conducting member.

13. In an electric apparatus, the combination with a movable member and means for actuating said member and normally in operative relation thereto, of dynamo-electric means for rendering said actuating means active in accordance with predetermined electrical conditions of said apparatus.

14:. In an electric apparatus, the combination with a movable member and means for actuating said member and normally in" operative relation thereto, of governing dynamo-electric means for rendering said actuating means active in accordance with predetermined electrical conditions of said apparatus, said governing means embodying normally balanced controlling means.

15. In an electric apparatus, the combi nation with a movable member and normally energized electrical means for actuating said member. of normally balanced means f r governing said electrical means in accordance with predetermined electrical conditions of said apparatus.

16. In an electric apparatus,,the combination with a movable member and means for actuating said member and normally in operative relation thereto, of a differentially wound and operating generator for governing said actuating means, and means responsive to a predetermined electrical condition of said apparatus for controlling the.

eifectiveness of said generator.

17. In an electric apparatus, the combination with a movable member and means for actuating said member and normally in operative relation thereto, of electrical governing means for said actuating means, and a differential relay for varying the efi'ectiveness of said governing means in accordance with predetermined electrical conditions of said apparatus.

18. In an electric furnace, an electrode, a motor for moving the electrode, a generator for supplying power to the motor, and means for varying the excitation of the enerator in accordance with the current owing through the electrode.

In testimony whereof, I have hereunto subscribed my name this thirty-first day of August, 1917.

HARRY HOLLIS. 

